Response of the equatorial ionosphere to solar magnetic sector crossing.

It has been found that the characteristics of the ionospheric and magnetospheric environment of earth are affected by the solar magnetic sector structure. Studies conducted at nonequatorial latitudes show that parameters such as F-region peak electron density and total electron content of the ionosphere undergo characteristic changes, depending on local time and season, in the vicinity of solar magnetic sector boundaries. No comparative studies have been reported, however, regarding the response of the equatorial ionosphere. The present investigation is concerned with the results which were obtained in a preliminary study regarding the nocturnal behavior of h-prime F at Kodaikanal (10 deg 14 min N, 77 deg 28 min E, dip 3.0 deg N) in relation to the sector boundary crossings. The quantity 'h-prime F' represents the minimum virtual height of F-region reflection. The current investigation demonstrates the response of the equatorial F region to solar magnetic sector structure during periods of high sunspot activity.